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Climate Change &
Health:
A Housing Case Study
He Kainga Oranga
University of Otago, Wellington
Professor Philippa Howden-Chapman, Dr Simon
Hales, Dr Nick Wilson, Helen Viggers
Why Housing?
• We spend about 90% of our time indoors –
the very old and very young may spend
almost 100% of their time indoors
• Housing (in some form) is a human universal
=> small changes at an individual level can
have a large total effect
• Housing is intended to protect us from the
environment
NZ Housing Context
• NZ houses are cold and damp, with
inadequate, often inefficient heating
• Average winter temperature is 16oC (WHO
recommends 18oC – 21oC)
• 1,000x rule
• 1600 excess winter deaths from respiratory
and circulatory problems, compared to 900
deaths attributable annually to traffic pollution
Modifying
influences
Health
Healtheffects
Effects
Temperature-related
illness and death
Extreme weatherExtreme
weatherrelated (floods,
storms,
related
health
effects
etc.) health effects
Human
exposures
Air pollution-related
health effects
Existing models
health impacts
Microbial changes:
Contamination
Regional of
weather
do not account
changesfor social or pathways
Contamination paths
Climate
technological changes
Change
Transmission dynamics
Transmission
•Heat waves
(adaptation)
dynamics
•Extreme weather
•Temperature
•Precipitation
Water and
and food-borne
food-borne
Water
diseases
diseases
Vector-borne
Vector
borne and
and
rodent
rodent- borne
borne diseases
diseases
Changes in agroecosystems, hydrology
Effects of food and
water shortages
Socioeconomic and
demographic disruption
Mental, nutritional,
infectious-disease and
other effects
Adaptation
• Adaptation is the adjustment in natural or
human systems in response to actual or
expected climate changes and their effects
• For social systems, adaptive capacity,
resilience and vulnerability all matter
• Projections come from past observation,
observed interventions and modelling
• Precautionary action essential & equitable
Outline
• Potential health effects – “2°C” scenario
• Local effects of heat, air pollution
• Altered infectious disease distribution (IPCC)
• Potential health effects – 4°C scenario
• Increase in above effects
• Likely major impact of global (incl. Pacific) social
disruption
• Adaptation measures (both scenarios)
• Housing, infrastructure (e.g. energy, water)
• Adaptation measures (high carbon scenario)
• “Lifeboat NZ”
Health effects of increasing
temperatures
• Warmer temperatures and increased rainfall
variability are likely to increase the intensity
and frequency of food-borne and water-borne
diseases.
• Higher than average temperatures lead to
~30% of reported European cases of
salmonellosis. In UK, monthly incidence of
food poisoning most strongly associated with
the temperatures occurring in the previous two
to five weeks.
Rise of respiratory diseases
• Rise of tuberculosis globally and nationally
• Crowding from population movement
increases transmission of TB
Baker M, Das D, Venugopal K, Howden-Chapman P. Tuberculosis associated with
household crowding in a developed country. Journal of Epidemiology Community
Health 2008;000:1–8:doi:10.1136/jech.2007.063610.
Health effects of increasing
temperatures
• Deaths in forest fires
• Impacts on aero-allergens and photochemical
smog in cities uncertain. Increase in bushfires
and smoke would increase hospital admissions
for cardio-respiratory conditions.
Drowning
• Number of people at risk from flooding by
coastal storm surges projected to increase
• Currently 75 million people at risk
• Projected 200 million in mid-range climate
scenarios (40cm rise in sea level by 2080s)
Extreme climate events
Extreme Climate Events
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Physical destruction
Immediate loss of life
Major life event / stressor
Ongoing effects if become a displaced
person
New Orleans
Taranaki
Niue
Malibu
Australia
Burundi
Britain,
Kaeo
Extreme climate event
Example Hurricane Katrina
• Structural factors affected poor black people
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most
Levees poorly maintained
Residentially segregated to low lying areas
Little public transport
Corruption, no functional emergency plan
Poor policy implementation
Water quality
• Increasing irregularity of supply
• Social gradient in water quality in New
Zealand
• Water metering and charging could further
increase inequalities and infectious diseases
• Households need right to minimum amount of
water at no charge -- important for cleanliness
and contagion control
Infectious disease
• Warmer temperatures and increased rainfall
variability are likely to increase food-borne
and water-borne diseases.
• Infectious agents (protozoa, bacteria and
viruses) and vector organisms (mosquitoes,
ticks and sand-flies) no thermostatic
mechanisms, so reproduction and survival
rates are strongly affected by fluctuations in
temperature.
Rise of infectious diseases
• Parts of the North Island likely to become
suitable for breeding of the mosquitoes that are
major dengue vector
• Much of NZ becomes receptive to other lessefficient vector species
• The risk of dengue in NZ likely to remain
below the threshold for local transmission
beyond 2050, under both scenarios.
Example – Dengue Fever
• No vaccine, no cure
• Lasts 7-10 days “bonebreak fever”
• Transmitted by Aedes aegypti, (a domestic,
day-biting mosquito). Typically people
might be bitten indoors in early morning or
evening.
Model of baseline transmission
(1961-1990 climate)
Model of future transmission
(2080s climate)
Heat-related diseases
• In Auckland and Christchurch, a small number
of heat-related deaths occur annually in people
aged over 65 and will increase (McMichael et
al., 2003).
• Current 1600 excess winter deaths likely to
decline
• N.B. European heat-waves in 2003 killed 70,000
people… epidemiological models did not predict
this scale of mortality
European Heat-wave, 2003
• Number of deaths in July and August, France, 1946 - 2004
from Toulemon and Barbieri, 2005
Deaths per day, France, August 2003
Observed and modelled summer temperatures
from Stott et al, 2004
Vulnerability
• People living in remote communities are likely
to be at increased risk due to their particular
living conditions and poor access to services.
• Relationship between drought, suicide and
severe mental health impacts in rural
communities
Not all have equal opportunity
Vulnerable populations have
• Low income and little wealth
• Less educated
• The very young and old
• Sole parents with children
• Those with chronic illnesses and disabilities
• Those living in socio-economically disadvantaged,
residentially segregated areas
• Those who suffer racial discrimination
Balance of Health Impacts?
• Most, not all, health impacts are expected to be
adverse
• Gains include: mosquito decline in some regions; lower
winter death-rates in some countries; increased food yields
in some regions
• Rapid change of mean temp by several degrees, over
decades, will cause widespread ecological stress and
physical changes
• Critical factor in recent Aust drought = extra 1 oC
• Weather extremes and disasters pose an additional
health hazard
Mayan Building,
Empire 1800BC – 1000 AD
How Can Housing Help?
Traditional housing has been designed for traditional
weather patterns / pests.
(e.g. mud in Nigeria, wood in Australia/ NZ)
• Mitigation – lowering carbon emissions
• Adaption – adapting to the changed environment
• Ignore – (& hope the problem will go away)
Ideas????
Overall,
e.g. heat wave
Individual
Urban
National
Short term
measures
Behaviour in
summer and
during
heatwave
Heat plan
Early warning
systems
Medium term
measures
A/C
Modify existing
buildings
Economic policy
(energy,
transport,
buildings)
Long term
measures
Passive cooling
Design of
buildings and
cities (including
transport?) reduce heat
islands
Energy
efficiency
standards.
Advantages
Disadvantages
Short term
measures
Cheap, immediate benefit
Can be implemented by
individuals
Inherently inequitable
Increase energy use and greenhouse gas
emissions
May be of limited public health benefit
Potential adverse health impacts of air
conditioning systems (buildingrelated symptoms); airborne
infections
Medium term
measures
Can be designed not increase
energy consumption, can be
implemented at building or
city scales
Moderately expensive
Effectiveness proven in case studies but
uncertain at urban or regional scale
Long term
measures
Reduced energy consumption
and greenhouse gas
emissions; Inherently
equitable, with major
potential health benefit
Costly (but cost effective?)
Long lead times
Requires political will (at international
level, in the case of climate change
mitigation)
Results
Mitigation – reduced carbon
emissions
• Low Carbon Building techniques
• Energy efficient design (Building Code)
- thermal envelope
- types of heaters
- “waste” heat
• Location
- solar gain
- transport
Example – energy efficiency
Forms of Heating - efficiency
• Fire
Open fire 15%
Enclosed fire -free-standing fire 25%
-basic double burner 65%
-hi efficienty dbl 85%
Gas (flued / unflued) 80%
Kerosene
• Other
Electricity -fan/oil column ~100%
-heatpump >100%
Solar
• None
Adaption at different societal levels
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Structural changes - shifting whole towns
Food production
Population movements - refugees
Urban design
Housing
Regulation of markets in energy & waterequity as well as efficiency
Adaptive capacity differs
• Capability and functioning both important
• Wealth, income, social and cultural capital
increase ability to adapt
• Adaptive responses should not increase
health inequalities
• Social gradients in health vs tipping point
Structural changes
• Location of settlements (in relation to
availability of secure water supplies, sea
level rise and extreme events)
• Infrastructure (water, electricity, transport,
communications) and ability to withstand
climate extremes
• Such as floods…
Urban Form
• 85% of New Zealander live in cities
• Urban sprawl increases carbon emissions
• Heat islands increase surrounding temperatures
~ 2°C, 5-11°C warmer than surrounding rural
areas
• People in suburbs and exurbs have longer
commutes & less exercise, more obesity
Adaptation
• Building Design
(moderate cold & heat / pest screens / materials / )
• Location
(flood plains/ low-lying coastal / exposure )
• Behaviour
But … leaky buildings in New Zealand partially
caused by importing Mediterranean style design,
without:
*ensuring builders knew how to build it well
*accounting for more mobile land.
Other examples of adaptation policy in
housing: a strong case for
• greater provision of extended family housing for
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families in chain migration
increases in social and health service
higher proportion of social housing in all regions
(presently only 5%)
ethnically integrated suburbs -strength of weak ties
Household right to minimum amount of water
important for cleanliness and contagion control
Greater use of grey water and rain water in cities
(with appropriate safeguards against mosquito
breeding)
Vince (2009) in
New Scientist: a
high carbon
world
Population movements:
NZ as lifeboat
• Worsening of extremes: floods, droughts,
storms, fires
• Sea level rise (esp Pacific islands, low lying
deltas)
• Reduced food security (esp Africa, Asia)
• Global solutions needed?
Co-benefits of NZ shifting to a lowcarbon
society
WIN/WIN policies
• More energy efficient housing benefiting health &
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education & reducing energy costs
Better support for active transport (cycling, walking)
will improve health (heart health, lower cancer risks
etc)
Cleaner non-carbon energy sources will reduce air
pollution
Improved urban design will have benefits for social
capital, mental health
Lower carbon diets (less meat) will reduce risks of
heart disease and cancer
Conclusions
• Health effects of climate change should be an
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important driver of adaptation policy
Predominant health effects through extreme
weather events & infectious diseases
Adaptation possible in urban form and housing
Building ‘linking social capital’ important
Co-benefits of moving to low-carbon economy
Possibility of positive contribution to GDP
Conclusions
• High carbon scenario likely to involve
major global social disruption.
• Can’t extrapolate health impacts in a simple
linear fashion…
• Need global optimisation of land use,
exchange of migration rights and food
security in return for protection of
“terrestrial commons”?
References
• Hales S, Black W, Skelly C, Salmond C, Weinstein P. Social deprivation and
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the public health risks of community drinking water supplies in New Zealand.
Journal of Epidemiology and Community Health 2003;57:581-583.
Hales S, Woodward A. Potential health impacts and policy responses. In:
Chapman R, Boston J, Schwass M, editors. Confronting Climate Change:
Critical issues for New Zealand. Wellington: Victoria University Press,
2006:117-123.
Hales S, Howden-Chapman P, Baker M, Menne B, Woodruff R, Woodward A.
Implications of global climate change for housing, human settlements and
public health. Review of Environmental Health 2007;22(4):295-302.
Hennessy, K., B. Fitzharris, B.C. Bates, N. Harvey, S.M. Howden, L. Hughes,
J. Salinger and R. Warrick, 2007: Australia and New Zealand. Climate Change
2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group
II to the Fourth Assessment Report of the Intergovernmental Panel on Climate
Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and
C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 507-540.
Schellnhuber (Copenhagen talk)
http://climatecongress.ku.dk/presentations/webcasts/
• “Confronting Climate Change: Critical Issues for
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New Zealand” edited by Ralph Chapman,
Jonathan Boston & Margot Schwass esp chap 11
Diamond, J. “Collapse: How societies choose to
fail or succeed”
Housing & Health programme website including
sustainable heater report
www.wnmeds.ac.nz/healthyhousing.html
Insulation study results www.bmj.com (search
“viggers” or “howden-chapman”)
Energy Efficiency & Conservation Authority
http://www.eeca.govt.nz/
Energy Studies Programme at Otago